U.S. patent application number 14/971035 was filed with the patent office on 2016-06-23 for wind power generation system.
The applicant listed for this patent is Hitachi, Ltd.. Invention is credited to Mitsuru SAEKI, Takashi SHIRAISHI, Junichi SUGINO.
Application Number | 20160177927 14/971035 |
Document ID | / |
Family ID | 54850338 |
Filed Date | 2016-06-23 |
United States Patent
Application |
20160177927 |
Kind Code |
A1 |
SAEKI; Mitsuru ; et
al. |
June 23, 2016 |
Wind Power Generation System
Abstract
A wind power generation system comprising: a wind power
generation equipment having a rotor which is operative to convert
energy of received wind to rotational energy, a nacelle which
supports the rotor rotatably, a tower which supports the nacelle
rotatably, a floating body which supports the tower and at least a
part of itself is positioned above the surface of the sea, a fixing
member which is installed or fixed on the sea bed, a mooring member
which couples the floating body and the fixing member, wherein the
mooring member is coupled to the floating body at place upward of
the center of gravity of the floating body and the wind power
generation equipment, and the floating body is practically
supported by one fixing member.
Inventors: |
SAEKI; Mitsuru; (Tokyo,
JP) ; SHIRAISHI; Takashi; (Tokyo, JP) ;
SUGINO; Junichi; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hitachi, Ltd. |
Tokyo |
|
JP |
|
|
Family ID: |
54850338 |
Appl. No.: |
14/971035 |
Filed: |
December 16, 2015 |
Current U.S.
Class: |
290/55 |
Current CPC
Class: |
B63B 2035/442 20130101;
F03D 13/25 20160501; Y02E 10/727 20130101; B63B 21/50 20130101;
F03D 13/22 20160501; F05B 2240/95 20130101; B63B 2021/505 20130101;
F05B 2240/2213 20130101; F03D 9/25 20160501; Y02E 10/72 20130101;
B63B 2035/446 20130101; F05B 2240/93 20130101 |
International
Class: |
F03D 11/04 20060101
F03D011/04; F03D 9/00 20060101 F03D009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 17, 2014 |
JP |
2014-254746 |
Claims
1. A wind power generation system comprising: a wind power
generation equipment having a rotor which is operative to convert
energy of received wind to rotational energy, a nacelle which
supports the rotor rotatably, a tower which supports the nacelle
rotatably, a floating body which supports the tower and at least a
part of itself is positioned above the surface of the sea, a fixing
member which is installed or fixed on the sea bed, a mooring member
which couples the floating body and the fixing member, wherein the
mooring member is coupled to the floating body at place upward of
the center of gravity of the floating body and the wind power
generation equipment, and the floating body is practically
supported by one fixing member.
2. The wind power generation system according to claim 1, wherein
the plural mooring members are provided and at least one of the
mooring members has a tension different from a tension of the other
mooring member(s).
3. The wind power generation system according to claim 1, wherein
the mooring member is singly provided.
4. The wind power generation system according to claim 1, wherein
the wind power generation system is of a downwind type where the
rotor is disposed on the leeward side of the nacelle.
5. The wind power generation system according to claim 4, wherein
the rotor has the plural blades disposed aslant to the leeward side
with respect to a rotor plane.
6. The wind power generation system according to claim 4, wherein
the rotor has the plural blades disposed aslant upward with respect
to the horizontal plane.
7. The wind power generation system according to claim 1, wherein
the mooring member is provided with at least one torsion preventive
coupling member for releasing the torsion of the mooring
member.
8. The wind power generation system according to claim 1, wherein
the mooring member is coupled to the floating body by means of a
rotary fastening member which is mounted to the floating body and
permits the rotation of the floating body.
9. The wind power generation system according to claim 8, wherein
the rotary fastening member is driven by a motor so that a position
of the rotary fastening member relative to the floating body can be
controlled.
10. The wind power generation system according to claim 1, wherein
the mooring member is coupled to the fixing member by means of a
rotary fastening member which is mounted to the fixing member.
11. The wind power generation system according to claim 1, wherein
the floating body is of a spar type having a substantially
cylindrical shape.
12. The wind power generation system according to claim 1, wherein
the floating body is of a semisubmersible type including an
assembly of plural substantially cylindrical structures.
13. The wind power generation system according to claim 1, wherein
the floating body has a cross section, at least a part of which is
substantially a rectangular shape or substantially a star-like
shape.
Description
CLAIM OF PRIORITY
[0001] The present application claims priority from Japanese Patent
application serial no. 2014-254746, filed on Dec. 17, 2014, the
content of which is hereby incorporated by reference into this
application.
[0002] 1. Technical Field
[0003] The present invention relates to a wind power generation
system and more particularly, to a floating wind power generation
system installed offshore.
[0004] 2. Background Art
[0005] Offshore wind power generation systems have become more
important from a viewpoint of worldwide demand for and economic
performance of renewable energy. Above all, it has become more
important to achieve the practical use of floating offshore wind
power generation systems constructible even in deep sea areas.
[0006] As shown in FIG. 11, a conventional floating offshore wind
power generation system is anchored to the seabed with three or
more mooring members in order to suppress pitch vibrations
(windwise vibrations), roll vibrations (across-wind vibrations) and
yaw vibrations (rotational vibrations) of a floating body.
[0007] However, an offshore construction work for setting up the
three or more mooring members substantially with an equal tension
lowers the economic performance of the floating offshore wind power
generation system. This triggers a strong demand for a floating
offshore wind power generation system that is anchored in place
with a single mooring member.
[0008] As to the floating offshore wind power generation system, a
technique such as set forth in Japanese Unexamined Patent
Application Publication No. 2005-526213 is known, for example.
Japanese Unexamined Patent Application Publication No. 2005-526213
discloses "a wind-driven electric power plant which is built afloat
at a deep sea area and includes: a machine room including an
electric generator; an adjustment device; a rotor shaft and a rotor
blade. The power plant has a structure where the above-described
machine room is mounted atop a tower that is anchored to the seabed
and basically afloat in an upstanding position because of the
gravity center of the whole wind mill located downward from the
center of buoyancy of the wind mill".
[0009] According to the wind-driven electric power plant of
Japanese Unexamined Patent Application Publication No. 2005-526213,
the large floating-type power generating wind mill installed
offshore can achieve sufficient stability for absorbing wind power
acting on the windmill rotor.
SUMMARY OF INVENTION
[0010] In the development of the floating offshore wind power
generation system, as described above, various approaches have been
taken to reduce installation costs of equipment for offshore
construction work and the like and to ensure that the wind mill on
the instable ocean can efficiently generate electric power by
receiving sufficient wind.
[0011] The floating offshore wind power generation system as
disclosed in Japanese Unexamined Patent Application Publication No.
2005-526213, for example, has the following problem. Since the
floating offshore wind power generation system is anchored to the
seabed with a single mooring member, the system can achieve more
reduction of the offshore construction work costs than the
conventional floating offshore wind power generation system
anchored with the three or more mooring members substantially of
the same tension. However, when the direction of ocean current or
the wind direction changes, it is difficult for the windmill to
catch the wind fully so that power generation efficiency may
fall.
[0012] There is also a fear that the whole body of the floating
offshore wind power generation system may become submerged when the
ocean current speed increases beyond the scope of assumption
because a bottom of the floating body is anchored to the seabed
with a single mooring member.
[0013] It is therefore an object of the present invention to
provide a floating offshore wind power generation system that is
adapted for efficient electric power generation as well as the
reduction of equipment installation cost.
[0014] According to the present invention for achieving the above
object, a wind power generation system comprising: a wind power
generation equipment having a rotor which is operative to convert
energy of received wind to rotational energy, a nacelle which
supports the rotor rotatably, a tower which supports the nacelle
rotatably, a floating body which supports the tower and at least a
part of itself is positioned above the surface of the sea, a fixing
member which is installed or fixed on the sea bed, a mooring member
which couples the floating body and the fixing member, wherein the
mooring member is coupled to the floating body at place upward of
the center of gravity of the floating body and the wind power
generation equipment, and the floating body is practically
supported by one fixing member.
[0015] The present invention can provide a floating offshore wind
power generation system that is adapted for the stable, efficient
electric power generation as well as the reduction of equipment
installation costs.
[0016] Problems, structures, and effects other than those described
above will be apparent with explanations of the following
embodiments.
BRIEF DESCRIPTION OF DRAWINGS
[0017] FIG. 1 is a general schematic diagram showing a wind power
generation system according to one embodiment of the present
invention;
[0018] FIG. 2 is a general schematic diagram showing a wind power
generation system according to one embodiment of the present
invention;
[0019] FIG. 3 is a general schematic diagram showing a wind power
generation system according to one embodiment of the present
invention;
[0020] FIG. 4A is a general schematic diagram showing a wind power
generation system according to one embodiment of the present
invention;
[0021] FIG. 4B is a diagram showing a rotary fastening member of
the wind power generation system according to one embodiment of the
present invention;
[0022] FIG. 4C is a diagram showing a rotary fastening member of
the wind power generation system according to one embodiment of the
present invention;
[0023] FIG. 5A is a general schematic diagram showing a wind power
generation system according to one embodiment of the present
invention;
[0024] FIG. 5B is a fragmentary sectional view of a tower of a wind
power generation system according to one embodiment of the present
invention;
[0025] FIG. 5C is a fragmentary sectional view of a tower of a wind
power generation system according to one embodiment of the present
invention;
[0026] FIG. 5D is a fragmentary sectional view of a tower of a wind
power generation system according to one embodiment of the present
invention;
[0027] FIG. 6 is a general schematic diagram showing a wind power
generation system according to one embodiment of the present
invention;
[0028] FIG. 7 is a general schematic diagram showing a wind power
generation system according to one embodiment of the present
invention;
[0029] FIG. 8 is a general schematic diagram showing a wind power
generation system according to one embodiment of the present
invention;
[0030] FIG. 9A is a diagram showing a torsion preventive coupling
member of a wind power generation system according to one
embodiment of the present invention;
[0031] FIG. 9B is a diagram showing a torsion preventive coupling
member of a wind power generation system according to one
embodiment of the present invention;
[0032] FIG. 10A is a diagram showing a cone angle of a downwind
type windmill;
[0033] FIG. 10B is a diagram showing a restorative force against, a
yaw deviation angle of the downwind type windmill; and
[0034] FIG. 11 is a general schematic diagram showing a
conventional wind power generation system.
DESCRIPTION OF EMBODIMENTS
[0035] The embodiments of the present invention will hereinbelow be
described with reference to the accompanying drawings. In the
drawings, like reference characters refer to the corresponding
components and the detailed description thereof is dispensed
with.
First Embodiment
[0036] First, a conventional wind power generation system is
described with reference to FIG. 11. FIG. 11 is a general schematic
diagram showing a downwind type floating offshore wind power
generation system.
[0037] As shown in FIG. 11, the conventional floating offshore wind
power generating system includes a floating body 5 floating on the
ocean, and a tower 4 mounted on the floating body 5 and serving as
a support pillar of the wind power generation system. A nacelle 3
incorporating an unillustrated electric generator is rotatably
mounted on the tower 4.
[0038] A rotor which includes a hub 2 and a plurality of blades 1
is rotatably mounted. to one end of the nacelle 3. The wind power
generation system is constructed such that this rotor receives wind
A and converts the received energy to rotational energy which is
transmitted to the electric generator for electric power
generation.
[0039] The floating body 5 is liable to be instable under the
influence of waves occurring on the sea surface 8 and the ocean
current. When the floating body 5 becomes instable offshore, the
wind power generation system mounted thereon, namely the windmill,
is also in an instable condition so as to be incapable of
efficiently receiving the wind A on the rotor. This results in
decreased power generation efficiency. In order to set the floating
body 5 in the stable condition as much as possible, a lower end of
the floating body 5 is coupled to a fixing member 7 secured to a
seabed 9 by means of a mooring member 6 made of a rigid rope, chain
or the like.
[0040] It is noted here that the conventional floating offshore
wind power generation system has three or more mooring members 6
respectively coupled to the plural fixing members 7 separately
secured to the seabed 9, as shown in FIG. 11. The three or more
mooring members 6 respectively interconnecting the floating member
5 and the fixing members 7 are set up substantially with an equal
tension. The stability of the floating body 5 and the wind power
generation system mounted thereon is ensured by setting up the
three or more mooring members 6 with substantially the same
tension.
[0041] As described above, the offshore construction work for
setting up the three mooring members with substantially the same
tension requires adjustment so that the cost of the construction
work is very high.
[0042] Next, a floating offshore wind power generation system
according to a first embodiment is described with reference to
FIGS. 1 and 2. FIGS. 1 and 2 are general schematic diagrams showing
a downwind type floating offshore wind power generation system
according to this embodiment. FIG. 1 shows a condition of the
floating offshore wind power generation system when the system is
on the dead calm sea or in breeze. FIG. 2 shows a condition of the
floating offshore power generation system when the system is under
a comparatively strong wind.
[0043] The floating offshore wind power generation system shown in
FIGS. 1 and 2 has the same structure as the floating offshore wind
power generation system of FIG. 11 in that the tower 4 serving as
the support pillar of the wind power generation system is mounted
on the floating body 5 floating offshore. Further, this wind power
generation system is also constructed the same way as the floating
offshore wind power generation system of FIG. 11 in that the
nacelle 3 incorporating the unillustrated electric generator is
rotatably mounted on the tower 4 and that the rotor including the
hub 2 and the plural blades 1 is rotatably mounted to one end of
the nacelle 3.
[0044] As shown in FIG. 1, the floating offshore wind power
generation system according to this embodiment has the floating
body 5 coupled to the fixing member 7 secured to the seabed 9 by
means of a single mooring member 6 and thus is anchored to the
seabed. It is noted here that the floating body 5 is coupled with
the mooring member 6 at place upward of the center of gravity of
the whole body of the floating offshore wind power generation
system that includes the floating body 5, and the wind power
generation system mounted thereon, which includes the tower 4, the
nacelle 3, the electric generator incorporated. in the nacelle 3,
and the rotor including the hub 2 and the plural blades 1 which are
disposed on the leeward side of the nacelle 3.
[0045] The rotor including the hub 2 and the plural blades 1 is
mounted as tilted upward in a manner that a plane interconnecting
tips of the plural blades 1, namely a rotor plane 10 has a tilt
angle 11.
[0046] The above-described structure permits the floating offshore
wind power generation system to be stably installed offshore even
though the floating body 5 is anchored to the seabed 9 with a
single mooring member 6.
[0047] Further, the power generation efficiency can be increased by
assembling the rotor tilted upward to form the tilt angle 11. As
shown in FIG. 2, the rotor can receive the maximum amount of wind
when, under the comparatively strong wind or the strong wind, the
whole body of the floating offshore wind power generation system
including the floating body 5 and the tower 4 is inclined toward
the leeward side.
Second Embodiment
[0048] A floating offshore wind. power generation system according
to a second embodiment is described with reference to FIGS. 3 and
9A. FIG. 3 is a general schematic diagram showing a downwind type
floating offshore wind power generation system according to this
embodiment. FIG. 9A shows an example of a torsion preventive
coupling member 12 shown in FIG. 3.
[0049] As described in the foregoing, the conventional floating
offshore wind power generation system has the structure less
affected by the direction of the ocean current or the wind
direction because the structure is stably anchored to the seabed by
means of three or more mooring members with substantially the same
tension. However, the floating offshore wind power generation
system illustrated by the first embodiment has the floating body 5
anchored to the seabed 9 by means of a single mooring member 6 and
hence, may encounter a problem. In a case, for example, where an
intensive whirlpool occurs undersea or where the wind direction
changes frequently, the whole body of the floating offshore wind
power generation system turns about a connection between the
mooring member 6 and the fixing member 7 as a fulcrum.
[0050] In this case, the mooring member 6 may be entangled with arm
unillustrated undersea cable, making the floating offshore wind
power generation system unable to keep its balance well on the
ocean. In consequence, the rotor fails to catch the wind A
efficiently, resulting in the decreased power generation
efficiency. There is also a fear that the floating offshore wind.
power generation system may drift away if the mooring member 6 or
the unillustrated undersea cable is broken.
[0051] In the floating offshore wind power generation system
according to this embodiment, as shown in FIG. 3, the single
mooring member 6 is provided with at least one torsion preventive
coupling member 12 so as to release torsion of the mooring member 6
in case that the mooring member 6 sustains torsion.
[0052] This ensures that the torsion in the mooring member induced
by the change in the ocean current direction or wind direction is
suppressed even though the floating offshore wind power generation
system is anchored to the seabed with the single mooring
member.
[0053] As shown in FIG. 9A, an arrangement may be made such that
the mooring member employs a mooring member 22 made of chain and
coupled with a cable 23 for transmitting the generated electric
power, and is provided with a torsion preventive coupling member 24
for releasing the torsion of the mooring member 22 and cable
23.
Third Embodiment
[0054] Now referring to FIGS. 4A to 4C, description is made on a
floating offshore wind power generation system according to a third
embodiment. FIG. 4A is a general schematic diagram showing a
downwind type floating offshore wind power generation system
according to this embodiment. FIGS. 4B and 4C each show an example
of a rotary fastening member 13 shown in FIG. 4A.
[0055] The second embodiment illustrates the example where the
mooring member 6 is provided with at least one torsion preventive
coupling member 12 for releasing the torsion in order to suppress
the torsion of the mooring member induced by the change in the
ocean current direction or the wind direction. This embodiment has
a structure where the floating body 5 is provided with a rotary
fastening member 13 which permits the rotation of the floating body
5, or a structure adapted to suppress the torsion of the mooring
member which is induced by the change in the ocean current
direction or the wind direction.
[0056] The mooring member 6 is coupled to the floating body 5 by
means of the rotary fastening member 13. This rotary fastening
member 13 is mounted to the floating body 5 in a manner to be
rotatable in a circumferential direction of the floating body
5.
[0057] As shown in FIG. 4B, the rotary fastening member 13 coupled
with the mooring member 6 is mounted to the floating body 5 via a
bearing 14. Because of the bearing 14 disposed between the rotary
fastening member 13 and the floating body 5, the rotary fastening
member 13 is free to rotate in the circumferential direction of the
floating body 5.
[0058] Even in the case where the floating offshore wind power
generation system is anchored to the seabed with the single mooring
member, as shown in FIG. 4B, the torsion of the mooring member
induced by the change in the ocean current direction or wind
direction can be suppressed by coupling the mooring member 6 to the
floating body 5 by means of the rotary fastening member 13.
[0059] Further as shown in FIG. 4C, a pinion gear 15 and a drive
motor 16 may be mounted to the rotary fastening member 13 such as
to electrically drive the rotary fastening member 13 to rotate on
the floating body 5. In this case, it is also possible, for
example, to detect the change in the ocean current direction or
wind direction by a sensor and to control the position of the
rotary fastening member 13 on the floating body 5 based on the
detection value.
[0060] As shown in FIG. 4C, the direction of the floating body 5
can be changed in accordance with the ocean current direction or
wind direction by electrically controlling the rotation of the
rotary fastening member 13. This also affords an effect to reduce
yaw control load of the floating offshore wind power generation
system mounted on the floating body 5.
Fourth Embodiment
[0061] A floating offshore wind power generation system according
to a fourth embodiment is described with reference to FIGS. 5A to
5D. FIG. 5A is a general schematic diagram showing a downwind type
floating offshore wind power generation system according to this
embodiment. FIGS. 5B to 5D each show a sectional view of the
floating body 5 taken on the line B-B' in FIG. 5A.
[0062] As shown in FIG. 5B, the floating offshore wind power
generation system according to this embodiment employs a spar type
floating body 5 having a substantially cylindrical configuration
such that a cross section of the floating body 5 is substantially
shaped like a circle. Thus, the resistance of the ocean current
against the floating body 5 can be minimized so that the torsion of
the mooring member induced by the change in the ocean current
direction can be suppressed.
[0063] Further, as shown in FIGS. 5C and 5D, the floating body 5
may be configured to have a substantially rectangular cross
sectional shape or a substantially star-like cross sectional shape
so as to be adapted to receive the resistance of the ocean current.
Thus, the floating offshore wind power generation system can obtain
an effect to attenuate vibrations occurring in the floating body
and the wind power generation system.
[0064] It is noted that the floating body 5 may be configured such
that the whole body of the floating body 5 has any one of the cross
sectional shapes shown in FIGS. 5B to 5D or that the floating body
5 partly has any one of the cross sectional shapes shown in FIGS.
5B to 5D.
Fifth Embodiment
[0065] A floating offshore wind power generation system according
to a fifth embodiment is described with reference to FIG. 6. FIG. 6
is a general schematic diagram showing a downwind type floating
offshore wind power generation system according to this
embodiment.
[0066] As shown in FIG. 6, a floating body of the floating offshore
wind power generation system according to this embodiment is a
semisubmersible floating body 20 composed of an assembly of plural
substantially cylindrical structures. This semisubmersible floating
body 20 is coupled with the mooring member 6. The semisubmersible
floating body 20 has a complicated configuration susceptible to the
resistance of the ocean current and hence, can stably float in the
sea. Thus the floating offshore wind power generation system is
obtained which is less prone to rolling even when anchored to the
seabed with a single mooring member 6.
Sixth Embodiment
[0067] A floating offshore wind power generation system according
to a sixth embodiment is described with reference to FIG. 7. FIG. 7
is a general schematic diagram showing a downwind type floating
offshore wind power generation system according to this
embodiment.
[0068] While the floating offshore wind power generation system
illustrated by the first embodiment is anchored to the seabed by
means of a single mooring member 6 coupling together the floating
body 5 and the fixing member 7 secured to the seabed 9, the system
of this embodiment is anchored by means of two mooring members 6
coupling together the floating body 5 and the fixing member 7
secured to the seabed 9.
[0069] As described in connection with the first embodiment, the
conventional floating offshore wind power generation system shown
in FIG. 11 requires high costs for the offshore construction work
thereof because the system has three or more mooring members
coupled to the separate fixing members 7 secured to the seabed
substantially with the same tension. On the other hand, the
floating offshore wind power generation system of this embodiment
has at least two mooring members 6 coupled to the same fixing
member 7.
[0070] It is noted here that the at least two mooring members 6 may
be coupled to the fixing member 7 substantially with the same
tension or may individually be coupled to the fixing member 7 with
different tensions. In a case where the two mooring members 6 are
individually coupled to the fixing member 7 with different
tensions, the cost for this offshore construction work can be
reduced as compared with the case where the mooring members are
coupled to the fixing member substantially with the same
tension.
[0071] According to the floating offshore wind power generation
system of this embodiment, the floating offshore wind power
generation system can be prevented from drifting away because even
when one of the mooring members 6 is broken, the other mooring
member 6 can moor the floating body 5.
Seventh Embodiment
[0072] A floating offshore wind power generation system according
to a seventh embodiment is described with reference to FIG. 8. FIG.
8 is a general schematic diagram showing a downwind type floating
offshore wind power generation system according to one
embodiment.
[0073] The floating offshore wind power generation system of the
sixth embodiment illustrates the example where the floating body 1
and one fixing member 7 are coupled together by means of at least
two mooring members 6. According to this embodiment, an additional
fixing member 7 is secured to the seabed 9 and the floating body 5
and the additional fixing member 7 are coupled together by means of
another mooring member 21 with a different tension.
[0074] Such an arrangement has an effect that when the ocean
current direction or the wind direction changes, the floating
offshore wind power generation system is changed in position so
that the tension of the mooring member 21 set up with the lower
tension is increased so much as to exceed that of the other two
mooring members 6 and hence, the floating body 5 is moored by the
mooring member 21.
[0075] Even in the case where both the mooring members 6 are
broken, the mooring member 21 can prevent the floating offshore
wind power generation system from drifting away, just as in the
sixth embodiment. Furthermore, the floating body 5 can be moored by
the mooring member 21.
[0076] It is noted that the floating body 5 coupled to the plural
mooring members may also be anchored to the seabed 9 practically
with one of the plural mooring members, as shown in FIG. 8.
[0077] It is also noted that the phrase "substantially one fixing
member" obviously refers to a case where there is only one fixing
member. In a case where there are plural fixing members, however,
the above phrase means that it may be supported basically by one
fixing member. In this case, there may be a transient state in
which the force for momentarily supporting the floating body
between a plurality of the fixed members is equally, however,
basically it is possible to support the floating body 5 by about
one fixing member. Note that it is practically supported by one
fixing member includes a transient state as described above.
[0078] In addition, the floating body 5 which is coupled to a
plurality of mooring members may be fixed to the seabed 9 by
practically one of the plurality of mooring members.
[0079] It is noted that the phrase "substantially one mooring
member" obviously refers to a case where there is only one mooring
member. In a case where there are plural mooring members, however,
the above phrase does not mean that all the mooring members are
kept in tension but means that what is required is to keep at least
one of the plural mooring members in tension. The mooring member
placed in tension can change depending upon the position of the
floating body. The concept for transient conditions is the same as
those on "one fixing member" as described above.
Eighth Embodiment
[0080] FIG. 9B shows an example of the fixing member 7 secured to
the seabed 9. The filing member 7 is provided with a rotary
fastening member 25 at an upper part thereof. The rotary fastening
member 25 is formed with an aperture (hole) through which the cable
23 passes. Further, the rotary fastening member 25 is coupled with
a mooring member 22 formed of chain. The rotary fastening member 25
assembled to the fixing member 7 is free to rotate on the fixing
member 7. The mooring member 22 formed of chain and the cable 23
are fixedly coupled with each other.
[0081] The torsion of the mooring member can be suppressed by
applying the fixing member 7 provided with the preventive measure
against the torsion of mooring member, as illustrated by this
embodiment, to the floating offshore wind power generation systems
illustrated by the first to the seventh embodiments.
Ninth Embodiment
[0082] A floating offshore wind power generation system according
to this embodiment is described with reference to FIGS. 10A and
10B. FIGS. 10A and 10B each show the nacelle 3 and the rotor, as
seen from above, of the floating offshore wind power generation
system illustrated by the first embodiment to the seventh
embodiment.
[0083] As shown in FIG. 10A, the rotor shape of the floating
offshore wind power generation system illustrated by the respective
embodiments may have a configuration where a plurality of blades
1a, 1b are assembled at a given angle (cone angle 26) to the hub 2
so as to allow the nacelle to be constantly directed in the wind
direction with respect to yaw rotation about an axis of the tower.
This cone angle 26 is an angle formed between a plane perpendicular
to an unillustrated main shaft of the rotor and the blade 1a (1b
).
[0084] By imparting this cone angle to the rotor of the floating
offshore wind generation system illustrated by the first embodiment
to the seventh embodiment, the nacelle can be directed in the wind
direction with respect to the yaw rotation or the rotation of the
windmill with respect to the tower axis.
[0085] In a case where the nacelle 3 and the rotor of the floating
offshore wind power generation system illustrated by the respective
embodiments rotate as angled at a given angle (yaw deviation angle
27) as shown in FIG. 10B, the blade 1b receives a greater thrust
force than the blade 1a inclined at the larger angle to the wind A
so that a yaw restorative force 28 is induced in the windmill,
directing the nacelle in the wind direction. Thus, the floating
offshore wind power generation system can maintain efficent
electric power generation.
[0086] As described above, the floating offshore wind power
generation systems of the first embodiment to the ninth embodiment
can provide a floating offshore wind power generation system that
is adapted for the stable, efficient electric power generation as
well as the reduction of offshore construction work costs for
equipment installation.
[0087] While each of the foregoing embodiments has been described
mainly taking the downwind type floating offshore wind power
generation system as an example, similar effects can also be
obtained by an upwind type floating offshore wind power generation
system.
[0088] The floating offshore wind power generation system can be
continuously operated even during power failure by adopting a
structure which can supply the electric power to a yaw control
mechanism from an auxiliary power supply such as an uninterruptible
power supply mounted to the floating offshore wind power generation
system. This auxiliary power supply can employ an electric storage
device, a diesel power generator, an engine generator, a tidal
power generator and the like, aside from the uninterruptible power
supply.
[0089] The present invention is not limited to the foregoing
embodiments but includes various modifications thereof. For
example, the foregoing embodiments have been described in detail
for the purposes of clarity of the present invention. The present
invention is not necessarily limited to embodiments that include
all the components described. Further, a part of the structure of
one embodiment is replaceable with a structure of another
embodiment. It is also possible to add a structure of one
embodiment to a structure of another embodiment. Further, a part of
the structure of each of the embodiments permits addition of or
replacement with another structure or deletion thereof.
REFERENCE SIGNS LIST
[0090] A . . . WIND [0091] 1, 1a, 1b . . . BLADE [0092] 2 . . . HUB
[0093] 3 . . . NACELLE [0094] 4 . . . TOWER [0095] 5 . . . FLOATING
BODY [0096] 6, 21, 22 . . . MOORING MEMBER [0097] 7 . . . FIXING
MEMBER [0098] 8 . . . SEA SURFACE [0099] 9 . . . SEABED [0100] 10 .
. . ROTOR PLANE [0101] 11 . . . TILT ANGLE [0102] 12, 24 . . .
TORSION PREVENTIVE COUPLING MEMBER [0103] 25 . . . ROTARY FASTENING
MEMBER [0104] 14 . . . BEARING [0105] 15 . . . PINION GEAR [0106]
16 . . . DRIVE MOTOR [0107] 17 . . . CIRCULAR CROSS SECTION [0108]
18 . . . RECTANGULAR CROSS SECTION [0109] 19 . . . STAR-LIKE CROSS
SECTION [0110] 20 . . . SEMISUBMERSIBLE FLOATING BODY [0111] 23 . .
. CABLE [0112] 26 . . . CONE ANGLE [0113] 27 . . . YAW DEVIATION
ANGLE [0114] 28 . . . YAW RESTORATIVE FORCE
* * * * *